Promise Technology Pegasus2 R6 18 TB full review

Apple may have inspired Intel to develop Thunderbolt, but it’s done little with the technology since. Besides the fitting of these promising high-speed data ports to practically every Macintosh (and one desktop monitor) over the last three years, it has been the work of other companies to make useful things to plug into them.

The very first company to sign up and release a Thunderbolt product was Promise Technology, a Taiwanese company specialising in professional storage hardware.

It was spring 2011, not long after the first Thunderbolted MacBook Pro appeared, that Promise delivered to the world the Pegasus R4 and R6. These were two multi-bay desktop RAID boxes, with four and six 3.5in disks inside respectively. Their only connection option was Thunderbolt. These units were aimed at video professionals who needed copious amounts of storage and demanded very quick transfer speeds for editing high-resolution video.

Now shortly after the appearance of Mk II Thunderbolt – formally known as Thunderbolt 2 of course – Promise Technology was also first to market with a Thunderbolt 2 product.

See also: Storage reviews

Three in fact, with updated versions of the original two Pegasus R6 units, and an additional 8-bay chassis too. We’ve also heard there will be a 4-bay unit named the Promise Pegasus2 M4 coming soon, using four 2.5in notebook disks or SSDs. These new RAID boxes are all now designated Pegasus2, with the annoyingly closed-up name.

The essential ingredients are the same. The Pegasus2 R6 that we tested is a sturdy unit resembling many popular NAS drives, only with all drive bays aligned horizontally and stacked upwards to form a tall tower – doubly so for the new eight-disk R8 version.

Disks are mounted in slide-in caddies, with mechanical levers on each tray to easily slide out the disks. These had a very smooth, oiled feel, more precise than your normal SMB-class NAS enclosure.

At the back of the box is one large fan to keep disks and supporting electronics cool, and a tinier aperture near the bottom to vent heat from the unit’s built-in fan-cooled power supply. In use we didn’t notice the fans as unduly noisy, with most background noise coming from the spinning disks.

Two Thunderbolt 2 ports are available, as we would hope, allowing the Promise Pegasus2 R6 to sit in the middle of a Thunderbolt data chain. A prime example would be a TB chain that starts at a Mac, onto a Pegasus2 and terminates with an external display.

Thunderbolt 2: The Sequel

Thunderbolt 2 is a modest evolution of the original Thunderbolt spec. Where the initial version allowed two separate channels with nominal 10 Gb/s speed – but full duplex, meaning data can flow at that speed in both directions simultaneously – the new Thunderbolt 2 has only one duplex channel, but with twice the nominal bandwidth, now at 20 Gb/s.

So the overall speed hasn’t changed, just the way the channels are configured: now we have something akin to line bonding, putting two slower channels together to create one faster channel.

Thunderbolt 1 could allow data to transfer in one direction at a maximum theoretical speed of 1250 MB/s. And in real use, we have seen speeds up to 869 MB/s; in fact, that was the best-case sequential read speed from the original Pegasus R6. Thunderbolt 2 should allow twice this speed – 2500 MB/s at the physical layer anyway, with actual user data throughput somewhere below this.

Promising Software

Promise Technology’s software utility for the Pegasus2 R6 gives clear and comprehensive control over many aspects of the drive’s functions

Beyond the tidy and precise build quality, there is another sign that Promise Technology has taken this product seriously. This is no me-too storage drive built by a box shifter.

That sign is the software utility with which you can setup and oversee the operation of the Pegasus2. This is a properly developed native OS X application with a wealth of detail about the internal parameters of the unit – such as internal temperatures, fan speeds, and plent of the minutiae of RAID setup.

Unlike most desktop RAID hardware made for the Apple Mac, the Promise Pegasus2 does not rely on software RAID to knit together the disks in that usual clever way we see in redundant arrays of independent disks.

Instead of just putting a number of disks in a box and leaving the Mac and its OS X Disk Utility application to stripe or mirror them, all the complex data shuffling is undertaken by dedicated RAID electronics inside.

Options are plentiful: you can configure as RAID 0, 1, 5, 6, 10 or 50. The latter two are nested RAID configurations, with RAID 50 perhaps the least familiar, comprising a pair of RAID 5 arrays, then striped together to enhance performance further.

Promise Pegasus2 R6: Performance

Our sample of the Promise Pegasus2 R6 landed with six 3.5in hard disks already installed, 3 TB Seagate Barracuda disks designated ST3000DM001 that spin at 7200 rpm and each have 64 MB of cache. These are high-performance desktop-class disks that first launched in 2011.

The combination of Pegasus2 R6 chassis with these six disks inside costs £2499. You can also find this Thunderbolt storage unit with 2 TB disks inside, totalling 12 TB of unformatted capacity, for £1849.

No empty-enclosure version is available, but with these older 3 TB Seagate disks selling for £80 each or less, it suggests the chassis could be priced at around £2000.

Initial results using the venerable Blackmagic Disk Speed Test were good but not world-shaking. We tried the range of files sizes available within the application, from 1 to 5 GB, and saw faster write speeds than read speeds – typically around 830 MB/s when writing but just 550 MB/s for reading.

Tested with Intech QuickBench and with a wider range of file sizes, recorded peak sequential results were much higher. Starting at the small level though, the Pegasus2 R6 showed healthy transfer speeds for random 4 KiB files, at 18 MB/s reading and 22 MB/s writing. Running random access tests with files from 4 to 1024 KiB, the overall average was 322 MB/s read, and 344 MB/s write.

To put those numbers into context, the latest Apple MacBook Pro (15-inch, Retina, Late 2013) has some of the fastest solid-state storage we’ve ever tested, connected directly to the machine’s PCIe bus. In the exact same test it averaged 196 and 328 MB/s for reads and writes respectively. So it was faster at the very smallest file level but by the 64 KiB level the Promise Pegasus2 was pulling ahead and resulted in the higher final overall random IO score; for single-threaded performance anyway.

The Promise drive measured well with larger sequential files in QuickBench, breaking the 1000 MB/s barrier comfortably with data from 2 to 10 MB size. Over this range it averaged 1172 MB/s reads and 1114 MB/s writes.

Best measured performance was found with AJA System Test benchmark. Using the application’s DiskWhackTest mode and 128 MB file size, the Pegasus2 R6 recorded 1313 MB/s reads and 1307 MB/s writes.

Power consumption was 23 W in idle standby, rising to 66 W under full test conditions.

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